The present invention relates to a milk-added coffee beverage produced through a step of heat sterilization using coffee and milk component as the raw materials, and to a process for producing it. More specifically, it relates to a stable and rich-flavored milk-added coffee beverage in which precipitation that occurs after heat sterilization treatment is prevented, and to a process for producing it.
A wide variety of milk-added coffee beverage products (hereunder referred to as “milk-added coffee beverages”) are known that are produced through a step of heat sterilization using coffee and milk components as the raw materials, and when classified according to the type of container these include canned beverages, PET bottled beverages, cardboard packed beverages and the like.
The common production steps for milk-added coffee beverages, in the case of canned milk-added coffee beverages for example, are “roasting”, “grinding”, “extraction”, “formulation”, “filtration”, “filling”, “rolling”, “sterilization”, “refrigeration” and “case packing”.
The “formulation” step is a critical step in terms of the quality of product in the milk-added coffee beverage production process. Specifically, when milk is directly added to coffee extract, the acidic pH of the coffee extract causes the milk to coagulate. It has been common in the past to add sodium bicarbonate to milk-added coffee beverages in order to prevent milk coagulation. Sodium bicarbonate is used because it is colorless and odorless, and has little effect on flavor.
The “sterilization” step is also a critical step in terms of the quality of product in the milk-added coffee beverage production process. In the sterilization step, heat sterilization is usually carried out for 20 minutes in a 250 g can at 125° C. (“Food Production/Distribution Data Handbook”, Japan Industry Research Institute Publication Center, p.720). However, milk-added coffee beverages tend to produce precipitation after heat sterilization, and although such precipitation poses no problem whatsoever in terms of the safety of the product, it considerably impairs the product value.
Adjustment in the amount of sodium bicarbonate added has been a common means used to prevent these problems, but this alone does not provide a sufficient anti-precipitation effect, and therefore addition of an emulsifier or thickening agent (stabilizer, thickener, etc.) has been necessary. However, while addition of an emulsifier or thickening agent provides an anti-precipitation effect, it is sometimes undesirable from the standpoint of the flavor of the milk-added coffee beverage, and has also raised the product cost. In addition, since a greater amount of coffee and milk components tends to result in easier precipitation after heat sterilization, it is necessary to increase the amount of emulsifier or thickening agent, and this has led to problems of further flavor impairment or cost increase. Depending on the formulation, even addition of an emulsifier or thickening agent fails to provide a sufficient anti-precipitation effect in many cases.
Japanese Unexamined Patent Publication HEI No. 7-184546 discloses a process for producing a stable coffee beverage which is characterized by subjecting a coffee extract to both treatment with mannanase and addition of alkali sodium or potassium salts, and particularly sodium bicarbonate.
Also, Japanese Unexamined Patent Publication HEI No. 8-228686 discloses a method of preventing precipitation of milk-added canned coffee which is characterized by adding a mixed emulsifier comprising a combination of emulsifiers each with a different HLB (hydrophilic-lipophilic balance).
In addition, Japanese Unexamined Patent Publication HEI No. 11-313647 discloses a method of preventing precipitation of milk-added canned coffee which is characterized by alkali-treating roasted coffee beans before extraction.
These methods all have their respective features, but an even simpler, more economical method has been desired.